In 2008, the World Health Organization (WHO) estimated that 1.4 billion adults worldwide were overweight; of these, 200 million men and 300 million women were obese. It is predicted that more than one billion people in the world will be obese by 2030. Obesity is a major cause for the development of debilitating conditions such as type 2 diabetes, cardiovascular disease, osteoarthritis (a health problem causing pain, swelling, and stiffness in one or more joints), stroke, hypertension, cancer (breast, colon, endometrial (related to the uterine lining), and kidney), and non-alcoholic steatohepatitis, all of which reduce life quality as well as lifespan.
Amongst healthcare experts around the world, there is now agreement that the global epidemic of obesity will be one of the leading causes of morbidity and mortality for current and future generations, unless the inexorable rise in the prevalence of this disorder is reversed. Once considered to be a problem mainly in Western cultures, developing nations have now joined the ranks of countries burdened by obesity. A 1999 United Nations study found obesity to be present in all developing regions and growing rapidly, even in countries where hunger also existed. Obesity is defined by the World Health Organization (WHO) as a subject who has a body mass index (BMI=weight in kg/height in m2) value of >30 kg m−2 (normal BMI=20-25 kg m−2).
Overweight and obesity result from an energy imbalance. The body needs a certain amount of energy (calories) from food to keep up basic life functions. Body weight tends to remain the same when the number of calories eaten equals the number of calories the body uses or “burns.” Over time, when people eat and drink more calories than they burn, the energy balance tips toward weight gain, overweight, and obesity.
A possible explanation for the rapid increase in obesity is that it is being driven by a combination of genetic, social and environmental factors. Although a significant proportion of people manage very successfully to maintain a healthy bodyweight by following a careful diet and having a reasonable level of physical exercise, for many others this plan has not resulted in the desired healthy outcome. For some of the obese population, pharmacotherapy will be required to provide the requisite adjunctive support to diet, exercise and lifestyle modification that will deliver a clinically beneficial bodyweight reduction of >5%.
There is no single cause of all overweight and obesity. There is no single approach that can help prevent or treat overweight and obesity. Treatment may include a mix of behavioral treatment, diet, exercise, and sometimes weight-loss drugs. In some cases of extreme obesity, weight-loss surgery may be an option. Over the last 15 years, only four new drugs, i.e. dexfenfluramine (Redux®), sibutramine (Meridia®, Reductil®), orlistat (Xenical®) and rimonabant (Acomplia®), have been registered for the treatment of obesity. Of these drugs, only three, dexfenfluramine, sibutramine and orlistat, have achieved global (with the exception of Japan) registration. There is a great need to develop additional anti-obesity drugs, which are safe and effective.